COS 21-5 - FHAST: A new modeling package for assessing habitat effects on anadromous fish.

Abstract: Anadromous fish are a vulnerable class of fishes as their requirement for both ocean and freshwater habitat exposes them to numerous threats. Among these threats are habitat changes that agencies, managers, and individuals implement on rivers to protect infrastructure, access water, develop agricultural land, etc. However, these same actors may also engage in habitat alterations focused on restoring habitat to aid in conservation of these species. When planning projects that could impact aquatic habitats either positively or negatively, an assessment of those impacts on native fauna, including fish, is generally required by regulatory agencies. These effects often involve numerous ecological interactions which are difficult to account for simultaneously. To aid in the assessment of habitat alteration effects on fish, we have developed the Fish Habitat Assessment and Simulation Tool (FHAST). FHAST is a spatially explicit agent-based model which allows users to simulate the effects of habitat alteration on an anadromous fish species of interest and account for numerous ecological processes. We present the model structure, user interface, and use FHAST to show results of how different habitat alterations such as changing cover, altering flows, or increasing food availability changes fish growth and population levels of both salmonids and sturgeons. We also show how habitat alterations can produce tradeoffs between growth and survival. We also present planned future additions to the model. With increasing access to habitat data and computing power, models like FHAST, which explicitly account for interacting ecological processes, will increasing become available and used.